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Chapter Summary
• Context: Surgical correction of spinal deformities has evolved significantly, shifting from purely mechanistic concepts based on distraction to a complex three-dimensional approach. The correction procedure represents one of the most critical moments of the operation. During the application of corrective maneuvers, manipulation of bony structures and stretching of the spinal cord impose a real and severe risk of permanent neurological injury. In addition to potential neuromuscular complications, the surgeon faces the constant challenge of selecting the most appropriate technical strategy for each patient given a diverse armamentarium of implants and instruments. Inadequate planning of correction can lead to failure in 3D curve control, fixation failures such as implant pull-out, and unsatisfactory cosmetic and functional outcomes. Therefore, comprehensive mastery of correction techniques and rigorous implementation of interprofessional safety protocols become indispensable.
• Chapter Objective: This chapter enables the reader to recognize and master the main operative techniques for spinal deformity correction, understanding their indications, specificities, and biomechanical limitations. By the end of the reading, the professional will be able to select and individualize the best surgical strategy, manage intraoperative neurophysiological events, and safely execute corrective and positioning maneuvers.
• Overview and FundamentalsHistorical Evolution and Implants Surgical treatment of deformities evolved from Harrington rods in the 1970s (focused on distraction) to segmental fixation with Luque sublaminar wires in the 1980s and Cotrel-Dubousset hook systems and hybrid constructs. The introduction of thoracic pedicle screws by Suk in the 1990s revolutionized 3D correction. Currently, the armamentarium encompasses hooks, sublaminar bands, and pedicle screws. Indications, Limitations, and Neurophysiological Monitoring Corrective maneuvers are indicated in scoliosis, kyphosis, and kyphoscoliosis. Technical limitations involve implant density, pull-out risk, and loss of neurophysiological signals. Intraoperative neuromonitoring is mandatory. Upon evoked potential signal loss, the protocol requires: technical check of the monitoring system; suspension of volatile anesthetics and neuromuscular blockers; optimization of mean arterial pressure and intravenous corticosteroid administration; irrigation of the surgical field with warm saline; immediate reversal of the last surgical maneuver performed. Surgical Planning and Positioning The patient is placed prone on chest and pelvic bolsters, keeping the abdomen free and preventing ocular, genital, and extremity compression. Operating table and fluoroscopy must be compatible, as well as the tabletop when neuronavigation is utilized. Instrumentation should include monoaxial or uniplanar screws, rod benders, compressors, distractors, and derotation towers for direct vertebral derotation (sequential or en bloc). Planning must correlate imaging studies with physical exam, paying attention to asymmetries such as shoulder balance.
• Step-by-Step Technical CorrectionFixation and Rods: Monoaxial or uniplanar screws are recommended at apical, neutral, and end levels. Longitudinal rods are contoured asymmetrically to reduce thoracic rib hump: hyperkyphosis on the concavity and hypokyphosis on the convexity. Cross-links are not necessary in pure screw-and-hook constructs. Distal Anchorage and Translation: The concavity rod is fixed at the distal point and translated progressively with reduction towers, distributing stress among fixation points. The convexity rod is placed next. Distal Adjustment and Derotation: The distal level is adjusted to ensure rotational neutrality and parallelism to the floor through direct derotation, compression, and distraction before definitive tightening. Apical Derotation and Finalization: The neutral vertebra is used as anchorage while applying direct derotation at apical levels (assisted by an assistant holding the neutral zone), combined with distraction on the concavity and compression on the convexity. After imaging confirmation and in situ adjustments, final rod locking is performed. Rib Resection: Costoplasty may be associated to reduce the thoracic rib prominence. Innovations Correction maneuvers still fundamentally depend on surgeon experience, as robotics and assisted navigation provide limited contribution during this specific phase.
• Clinical Application: Practical application guides all phases of spinal deformity patient management. Preoperatively, imaging is correlated with physical exam to avoid postoperative cosmetic asymmetries, such as shoulder imbalance. In positioning, correct bolster arrangement and protecting prominences, eyes, and genitalia prevent severe complications associated with the prone position. During surgical execution, using monoaxial or uniplanar screws at key points enables effective application of direct vertebral derotation and translation maneuvers. Gradual distribution of reduction forces prevents bone-implant interface failure (pull-out). If neurophysiological alerts occur, the surgeon must lead sequential execution of the rescue protocol in concert with anesthesiologist and neurophysiologist, restoring hemodynamics and reversing corrective maneuvers when needed to prevent permanent neurological deficits.
